Related papers: Electro-strong interaction and high Q^2 events at …
Deep-inelastic e^\pm p scattering at high squared momentum transfer Q^2 up to 30000 GeV^2 is used to search for eq contact interactions associated to scales far beyond the HERA centre of mass energy. The neutral current cross section…
A contact four-fermion interaction between light quarks and electrons has been evoked as a possible explanation for the excess of events observed by HERA at high-$Q^2$. We explore the 1-loop effects of such interaction in $\Gamma(Z^0 \to…
From 1992 to 2007, HERA, the first electron-proton collider, operated at cms energies of about 320 GeV and allowed the investigation of deep-inelastic and photoproduction processes at the highest energy scales accessed thus far. This review…
Recent results from the HERA ep collider are reviewed in these proceedings. The results are from measurements that probe QCD at high-energy scales, as defined by $Q^2$, the four-momentum-transfer squared of the collisions. These…
HERA, the first electron-proton collider, has been delivering luminosity since 1992. It is the natural extension of an impressive series of fixed-target lepton-nucleon scattering experiments. The increase of a factor ten in center-of-mass…
A review is given of the measurements of the hard diffractive interactions in recent years from two high-energy colliders, the HERA $ep$ collider and the Tevatron $p\bar{p}$ collider. The structure of the diffractive exchange in terms of…
The HERA collider with its center of mass energy of 318 GeV makes it possible to study a wide range of electroweak physics as well as to search for physics beyond the Standard Model (SM). In this article, recent results, obtained by the two…
Photon-proton ($\gamma p$) interactions with~$Q^2<10^{-2}$~GeV$^2$ and deep-inelastic scattering ($\gamma^* p$) interactions with photon virtualities $Q^2>5$~GeV$^2$ are studied at the high energy electron-proton collider HERA. The…
The kinematic reconstruction of neutral current high Q^2 events at HERA is discussed in detail using as an example the recently published events of the H1 and ZEUS collaborations at Q^2 > 15000 GeV^2 and M > 180 GeV, which are more numerous…
The luminosity of the electron-proton collider, HERA, will be increased by a factor of five during the long shutdown starting September 2000. At the same time longitudinal lepton beam polarisation will be provided for the collider…
Multi-electron and multi-muon production have been measured at high transverse momentum in electron-proton collisions at HERA.Good overall agreement is found with the Standard Model predictions, dominated by photon-photon interactions.…
Data from the Large Electron Positron collider (LEP) at CERN on hadron production in gamma-gamma interactions exceed the predictions of the standard model by an order of magnitude at the highest observed transverse momenta in three…
The reaction e+p --> e+X is studied with the H1 detector at Hera. The data cover momentum transfers Q^2 between 200 GeV^2 and 30,000 GeV^2 and correspond to an integrated luminosity of 35.6 pb^(-1). The differential cross section…
A search for physics beyond the Standard Model in neutral current deep inelastic scattering at high negative four-momentum transfer squared Q^2 is performed in e^{\pm}p collisions at HERA. The differential cross section ds/dQ^2, measured…
A search for physics beyond the Standard Model has been performed with high-Q^2 neutral current deep inelastic scattering events recorded with the ZEUS detector at HERA. Two data sets, e^+ p \to e^+ X and e^- p \to e^- X, with respective…
Recent results from searches for physics beyond the Standard Model (SM) in electron/positron-proton collisions at HERA at center-of-mass energies of 300 and 320 GeV are presented. They were performed on a data sample collected in the period…
The luminosity of the electron-proton collider, HERA, will be increased by a factor of five during the long shutdown in the year 2000. At the same time longitudinal lepton beam polarisation will be provided for the collider experiments H1…
Data from HERA, LEP and the Tevatron, as well as from low energy experiments are used to constrain the scale of possible electron-quark contact interactions. Different models are considered, including the most general one, in which all new…
Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb^{-1}. The observed numbers of events are in general agreement with…
Striking events with isolated charged leptons, large missing transverse momentum and large transverse momentum of the hadronic final state were observed at the electron proton collider HERA in a data sample corresponding to a luminosity of…